Need A/C in trailer. No idea what im doing.

[MikeJ]

Hello everyone, I hope all who read this are well!

Long story short, I bought an enclosed utility trailer to do some traveling in. The previous owner decked it out with solar, but it is not enough to run the current stand alone ac unit that's in it. It's 13,000 btu's, which is way overkill for 40 square feet anyway.

I only have the slightest idea of what is currently going on in it. The guy I bought it from "was selling it for his friend" who he very inconveniently "can't get ahold of" for me to ask him about the build. It has one single 12v (I think) marine battery, an unknown W solar panel, a 410W schumacher power converter, and wanderer solar charge controller.

I really know next to nothing about solar. I honestly always just though you plugged stuff into solar panels and it ran them.

My goal is to have a small ac unit (I'm not even sure what the smallest available ac unit is) that will run while I'm sleeping (5-8 hours a night).

Any and all help and guidance is much much appreciated. Thank you very very much!

 

[snoobler]

Welcome to the forum.

Check out the Will's videos on his solar shed. Similar size and power needs:

https://www.youtube.com/c/WillProwse/search?query=solar%20shed

Running even that small A/C all night will likely require a substantial upgrade and carry significant cost.

 

[Greggo]

Small 5 or 6k btu and a 2000 watt honda will idle 9 hrs on 1 gallon of gas. I know it's not solar but just wanted to throw that out there. Way cheaper.

 

[Bubba1]

Small 5 or 6k btu and a 2000 watt honda will idle 9 hrs on 1 gallon of gas. I know it's not solar but just wanted to throw that out there. Way cheaper.

Often you only need the AC for a few hours around sunset if you have any insulation. Worked for me on a boat in south louisiana

 

[MikeJ]

Welcome to the forum.

Check out the Will's videos on his solar shed. Similar size and power needs:

https://www.youtube.com/c/WillProwse/search?query=solar%20shed

Running even that small A/C all night will likely require a substantial upgrade and carry significant cost.

I actually did watch that video, but he used alot of terminology I didn't know or understand.

 

[MikeJ]

Small 5 or 6k btu and a 2000 watt honda will idle 9 hrs on 1 gallon of gas. I know it's not solar but just wanted to throw that out there. Way cheaper.

Those really quiet Honda generators are like 1000 bucks new. Roughly How much is what would be needed to do a solor system capable of running a 5k btu 8 hours max a night. I wanted to get an ac that has a thermostat so it turns off when it reaches temperature. It may only run for like an hour or two total during the span of my sleep.

 

[MisterSandals]

It has one single 12v (I think) marine battery, an unknown W solar panel, a 410W schumacher power converter, and wanderer solar charge controller.

Lets try to figure out what you have. Do you have any pics? Can you get a pic of the spec label on the panel or a measurement of its size?

Roughly How much is what would be needed to do a solor system capable of running a 5k btu 8 hours max a night.

From recollection, i think the small window units run at about 600w. So lets run some numbers with that (someone chime in with better numbers please):

600w x 8h = 4800wh
4800wh / 12.8v = 375ah from batteries. Double that for lead acid because only 50% dischargeable.

Recharging, assuming 5 good solar hours:
4800wh / 5h = 960w of solar panels.

 

[MikeJ]

Lets try to figure out what you have. Do you have any pics? Can you get a pic of the spec label on the panel or a measurement of its size?


From recollection, i think the small window units run at about 600w. So lets run some numbers with that (someone chime in with better numbers please):

600w x 8h = 4800wh
4800wh / 12.8v = 375ah from batteries. Double that for lead acid because only 50% dischargeable.

Recharging, assuming 5 good solar hours:
4800wh / 5h = 960w of solar panels.

I can take some pictures when I get home, for sure! How much money would 1000W of solar panels and all other necessary implements cost? Would buying a generator be cheaper?

 

[snoobler]

Lets try to figure out what you have. Do you have any pics? Can you get a pic of the spec label on the panel or a measurement of its size?


From recollection, i think the small window units run at about 600w. So lets run some numbers with that (someone chime in with better numbers please):

600w x 8h = 4800wh
4800wh / 12.8v = 375ah from batteries. Double that for lead acid because only 50% dischargeable.

Recharging, assuming 5 good solar hours:
4800wh / 5h = 960w of solar panels.

$1100 for LFP cells/BMS (5700Wh usable)
$400 for PSW 2000W inverter
$500 for MPPT (need 80A)
$500 for Solar panels.
$100 for misc

$2600

You could save a couple hundred by going with 24V and only needing 40A of MPPT.

 

[Hedges]

Yes, around 600W for a window air conditioner. I have one rated 5k BTU and 440W that I took measurements of.
It would require about 2000W from the inverter for starting surge.

Is 600w enough

I plan on putting 600w of solar panels on the roof of a small camper. The Panels will be able to tilt so I can get as much power as I can. My main use is to run a 5000 BTU AC tha draws 450w in the summer and a 500w space heater in the winter & a few little items like phones, tablets and led...

diysolarforum.com

You can choose lead-acid for simplicity, but might get only one or two years out of it if cheaper batteries and run down to 50% DoD every night. Could be several years if only a few months out of the year.

Two of these for $1400 would give you 12V 376 Ah (8 hour rate). Vendor indicates 600 cycles to 75% DoD, which could be 4 to 8 years if used 6 months or 3 months per year.

http://sunxtender.com/solarbattery.php?id=30

You can buy pre-assembled lithium batteries that should last longer, but they are pretty expensive for new products. There are some companies selling batteries built from recycled cells which cost less.
I think you can assemble DIY LiFePO4 12V 3600 Wh for around $500, 12V or 24v 7200 Wh for around $1000.
Make sure your BMS/battery can deliver the current for starting surge, about 200A at 12V.

I can take some pictures when I get home, for sure! How much money would 1000W of solar panels and all other necessary implements cost? Would buying a generator be cheaper?

Generator would be cheaper.
1000W of solar panels is even cheaper, could be about $200, but everything else in a PV system costs much more.

There is a crossover point between PV, grid, generator depending on how long it will be used.
A generator is going to cost $0.50/kWh long term.
Grid ranges from $0.05 to $0.50, mostly based on location.
PV costs $0.025 to $0.05, and batteries cost $0.05 to $0.50 (depending on chemistry and vendor or DIY). Battery inverters vary in price depending on quality and capability.

 

[Bubba1]

Buy the Honda generator and your done. Chain it to a tree a little away and you will barely hear it.

 

[snoobler]

Generator is $1000 + $3/night (assuming about a gallon of gas and $3/gal).

An extra $1600 in fuel will be spent in 1600/3 = 533 nights, i.e., after 533 nights, the generator will cost you more than the solar.

 

[Hedges]

i.e., after 533 nights, the generator will cost you more than the solar.

Three to eight years break-even, depending on the number of nights to run. (or 1.5 years if you live in a year-round desert.)

Solar is a clear winner for some applications and users, while a generator is for others. Also it is a single, man-portable device.
Would be nice to have an inverter generator with PV input, so you could gradually add solar power and reduce fuel consumption, at least for daytime use.

 

[John Frum]

A generator is a good solution to the multiple days of autonomy problem.
Generators are noisy, dirty, smelly, maintenance is a pain and fuel is expensive, but if you need power and the sun won't cooperate its really nice to have.

 

[MikeJ]

Lets try to figure out what you have. Do you have any pics? Can you get a pic of the spec label on the panel or a measurement of its size?


From recollection, i think the small window units run at about 600w. So lets run some numbers with that (someone chime in with better numbers please):

600w x 8h = 4800wh
4800wh / 12.8v = 375ah from batteries. Double that for lead acid because only 50% dischargeable.

Recharging, assuming 5 good solar hours:
4800wh / 5h = 960w of solar panels.

Sorry it took so long for me to get back with the pictures. So here is what is here:

The solar panel is roughly 19"x42". I can't see anything on the back of it cause it is mounted so close to the roof of the trailer. The brand and I guess the serial number are pictured.

It has a 410w power converter.

A wanderer solar charger controller.

This thing that has the voltage of the battery (I assume).

And then lastly there's the battery. Based on the model number of the battery I thought it might be a 24v, but the highest I've seen the readout is 14v, so I don't know what the battery is.

 

[MikeJ]

Three to eight years break-even, depending on the number of nights to run. (or 1.5 years if you live in a year-round desert.)

Solar is a clear winner for some applications and users, while a generator is for others. Also it is a single, man-portable device.
Would be nice to have an inverter generator with PV input, so you could gradually add solar power and reduce fuel consumption, at least for daytime use.

The Honda generator i was looking at is an inverter. What does pv input mean?

 

[MisterSandals]

The solar panel is roughly 19"x42".

That sounds like a standard Renogy 100w panel.

A wanderer solar charger controller.

Pretty standard. 30a model?

My goal is to have a small ac unit (I'm not even sure what the smallest available ac unit is) that will run while I'm sleeping (5-8 hours a night).

The small window units that folks talk about are 600w-ish. And inverter will be 85% efficient so lets call it 700+ watts.

So to run that for 8 hours:
8h x 700w = 5600wh

With an average of 5 hours of quality solar a day you'd need:
5600wh / 5h = 1120w of solar panels. So roughly 12x what you have.

Your charge controller would need to charge at:
1120w / 12.8v = 87.5a (operating at 100% efficiency)

You would need quite a few more batteries as you'd need to store all 5600wh until evening:
5600wh / 12.8v = 437ah usable. Lead acid is 50% usable so you'd need 900ah of batteries.

Your inverter would need to be at least 1000w, maybe more to handle the startup amps.

 

[MikeJ]

That sounds like a standard Renogy 100w panel.


Pretty standard. 30a model?

The small window units that folks talk about are 600w-ish. And inverter will be 85% efficient so lets call it 700+ watts.

So to run that for 8 hours:
8h x 700w = 5600wh

With an average of 5 hours of quality solar a day you'd need:
5600wh / 5h = 1120w of solar panels. So roughly 12x what you have.

Your charge controller would need to charge at:
1120w / 12.8v = 87.5a (operating at 100% efficiency)

You would need quite a few more batteries as you'd need to store all 5600wh until evening:
5600wh / 12.8v = 437ah usable. Lead acid is 50% usable so you'd need 900ah of batteries.

Your inverter would need to be at least 1000w, maybe more to handle the startup amps.

So basically I would need ALOT more of every aspect involved to run an ac? A Good condition used Honda 2200w inverter generator runs around 700-900 bucks. Brand new is 1100. I'm only going to be gone for 2 months. Would all the added stuff I need cost more than 1100?

 

[MisterSandals]

Would all the added stuff I need cost more than 1100?

Yes almost certainly. Air conditioning is the holy grail that so many seek to run with solar. Its always a rude awakening how much power it requires (yet everybody knows it makes electricity bills soar).

Sometimes you're forced to go solar if you cannot run a generator at night in a campground for example.
The peacefulness of solar is quite nice, i hate generators.

But for 2 months, i think a generator is likely the cheapest and easiest.

 

[Hedges]

The Honda generator i was looking at is an inverter. What does pv input mean?

Photo Voltaic input.

"Solar generators" are batteries with an inverter, and they have a jack where photovoltaic panels can be connected to recharge.

Considering inverter generators have a generator charging a DC rail and an inverter, would be nice if we could connect photovoltaic panels to them, let the sun provide some or all needed power during the day. But not a product I'm aware of. Would be a neat DIY project.